The present invention relates to apparatus for treatment of articles as they are conveyed serially through a controlled environment, and more particularly to a refrigeration enclosure including an endless helical conveyor for serially carrying food items within the enclosure as they are frozen.
An endless conveyor, mounted inside a treatment enclosure and forming a helical path, is known to be useful for continuously and serially transporting items along the path as they are treated within the enclosure. The helical portion of the conveyor can be driven at a controlled velocity to treat each food item for a predetermined length of time as it traverses the helix. One arrangement is shown in U.S. Pat. No. 4,103,768 (Persson), including an endless belt mounted on a perforated revolving drum. A cooling or other treating apparatus is mounted inside the drum. The belt is supported movably on low friction blocks. U.S. Pat. No. 4,023,381 (Onodera) discloses a drum rotated by a drive motor. A cooler inside the drum includes a tube or coil. As seen from FIG. 3 of the patent, the endless belt includes chain-like members supported by rods extending transversely across the belt.
In U.S. Pat. No. 3,666,083 (Smith), an endless conveyor in a refrigerating unit includes a pair of chains, one radially outward of the other, connected by a series of crossrods which support the articles to be frozen. The conveyor is disposed about a pair of rotating drums, and is supported on a rail. A low friction layer is positioned between the conveyor and the supporting rail. U.S. Pat. No. 3,315,492 (Dreksler) shows a food refrigerating apparatus in which an endless conveyor belt is supported by parallel rails 36, to assume a helical path. The parallel rails are supported by horizontal and transverse arms. Spacers (FIG. 5) keep the rails parallel to one another. The apparatus includes a central drum, which preferably is rotated in the direction of conveyor belt travel to minimize friction between these members.
While perhaps satisfactory in many respects, the above devices require massive rotating drums, and means for rotating the drums with respect to stationary refrigeration housing. The rotating drum is a source of undue complexity, increased bulk, and interferes with circulation of cooling air throughout the enclosure.
Therefore, it is an object of the present invention to provide a treatment apparatus with an open, stationary framework for supporting a moving endless conveyor in a helical path.
Another object of the invention is to provide a fixed, low friction support inside an enclosure for supporting an endless conveyor for movement relative to the enclosure, eliminating the need for a revolving drum inside the enclosure.
Yet another object is to provide a substantially rigid helical support assembly, formed of a plurality of flexible bands assembled onto a series of radially directed substantially rigid rods, for supporting an endless conveyor in a helical path in a simple, open frame structure to minimize the framework weight and interference with air circulation within an enclosure.